Oxazoline hot melt ink compositions

ABSTRACT

An ink composition comprised of a colorant and a vehicle component, and which vehicle component is comprised of the condensation product of an organic acid and an amino alcohol.

This application is a continuation of application Ser. No. 08/719,532,filed Sep. 27, 1996 now U.S. Pat. No. 5,698,017.

PENDING APPLICATIONS AND PATENTS

Hot melt inks for acoustic jet printing are illustrated in patents andcopending applications U.S. Pat. No. 5,688,312; U.S. Pat. No. 5,747,554and U.S. Ser. No. 641,866, the disclosures of each application beingtotally incorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention is directed to ink compositions and, morespecifically, the present invention relates to hot melt inks especiallyuseful for acoustic ink printing, processes and apparatuses, reference,for example, U.S. Pat. No. 5,121,141, U.S. Pat. No. 5,111,220, U.S. Pat.No. 5,128,726, U.S. Pat. No. 5,371,531, and U.S. Ser. No. 176,381 nowabandoned, the disclosures of which are totally incorporated herein byreference, including especially acoustic ink processes as illustrated insome of the aforementioned copending applications and patents, such asan acoustic ink printer for printing images on a record medium.

More specifically, the present invention is directed to hot meltacoustic ink compositions wherein there can be generated with such inksexcellent developed images with acceptable image permanence, excellentprojection efficiency on transparencies without a post fusing step, andexcellent crease resistance, pen-offset resistance, nonsmearing, highprojection efficiency, and wherein the inks possess acceptable, and inembodiments superior lightfastness and superior waterfastness. Moreover,in embodiments of the present invention there is enabled theelimination, or minimization of undesirable paper curl since water isnot present, or very small amounts thereof are selected, in theinvention inks, and it is preferred that there be an absence of water,and since water is not present in the inks a dryer can be avoidedthereby minimizing the cost and the complexity of the acoustic ink jetapparatus and process. The inks of the present invention in embodimentsthereof are comprised of a colorant and a vehicle derived from thecondensation product of an organic acid and an amino alcohol with theoptional presence of a polycondensation catalyst, and which condensationreaction is accomplished at elevated temperature such as from about 150°to about 180° C. The invention ink vehicle possesses, for example,desirable viscosities, for example 1 to about 25, and about 5 centipoiseat suitable temperatures, for example from about 120° to about 150° C.,acceptable acoustic loss, and improved hardness or penetration. Theaforementioned vehicle is comprised in embodiments of the reactionproduct of an organic acid and amino alcohol, such as an oxazoline,amide and/or amino ester as illustrated herein, reference for exampleFormula 1, and wherein R₁ is an aliphatic, for example alkyl of 1 toabout 55 carbon atoms such as ethyl, propyl, butyl hexyl, stearyl andthe like, R₂, R₃, R₄ and R₅ are an aliphatic group, for example alkyl of1 to 55, such as ethyl, propyl, butyl, hexyl, stearyl, oralkylene-ester, such as ethylene acetate or methylene stearate, or analcohol from about 2 to about 6 carbon atoms, such as methanol, ethanol,propanol and the like. It is believed that the major product from theaforementioned condensation is an oxazoline or benzoxazolineillustrated, for example, by Formulas or structures I and Ia,respectively, and present in the ink in an effective amount of fromabout 65 to about 100 percent by weight of the condensation product, andpreferably from about 85 to about 100 percent of the condensationproduct. The minor constituents of the condensation product are anamide, as illustrated by structure II or IIa, or amino ester asillustrated by structure III, or mixtures thereof present in the productin amount of from about 0 to about 35 percent by weight, and preferablyfrom about 0 to about 15 percent by weight of the condensation product.With mixtures from about 1 to about 99 weight percent or parts of theamide, and from about 99 to about 1 weight percent or parts of the aminoester are present in embodiments. ##STR1##

In acoustic ink printing, the printhead produces approximately 2.2picoliter droplets by an acoustic energy process. The ink under theseconditions should preferably display a melt viscosity of about 5 toabout 25 centipoise or less at the jetting temperature. Furthermore,once the ink is jetted onto the paper, the ink image should possessexcellent crease properties, and excellent pen non-offset properties,and should be nonsmearing waterfast, of excellent transparency, andexcellent fix qualities. In selecting an ink for such applications, itis desirable that the vehicle display a low melt viscosity, such as fromabout 1 centipoise to about 20 centipoise in the acoustic head, whilealso displaying solid-like properties after being jetted onto paper.Since the acoustic head can effectively tolerate a temperature up toabout 180° C., and preferably up to a temperature of from about 142° C.to about 160° C., the vehicle for the ink should preferably displayliquid-like properties, such as a viscosity of 1 to about 10 centipoiseat a temperature of from about 110° C. to about 165° C., and solidify orharden after jetting onto paper, such that the ink displays a hardnessvalue of from about 0.1 to about 0.5 millimeter utilizing a penetrometeraccording to the ASTM penetration method D1321.

Ink jet printing processes that employ inks that are solid at roomtemperature and liquid at elevated temperatures are known. For example,U.S. Pat. No. 4,490,731, the disclosure of which is totally incorporatedherein by reference, discloses an apparatus for dispensing certain solidinks for printing on a substrate such as paper. The ink dye vehicle ischosen to have a melting point above room temperature so that the ink,which is melted in the apparatus, will not be subject to evaporation orspillage during periods of nonprinting. The vehicle selected possesses alow temperature to permit the use of the solid ink in a thermal ink jetprinter. In thermal ink jet printing processes employing hot melt inks,the solid ink is melted by a heater in the printing apparatus andutilized as a liquid in a manner similar to that of conventional thermalink jet printing. Upon contact with the printing substrate, the moltenink solidifies rapidly enabling the dye to remain on the surface insteadof being carried into the paper by capillary action, thereby attemptingto enable higher print density than is generally obtained with liquidinks. Hot melt ink jets are somewhat similar to thermal ink jets,however, a hot melt ink contains no solvent. Thus, rather than beingliquid at room temperature, a hot melt ink is typically a solid orsemi-solid having a wax-like consistency. These inks usually need to beheated, for example, to approximately 100° C. before the ink melts andconverts into a liquid. With hot melt inks, a plurality of ink jetnozzles are provided in a printhead. A piezoelectric vibrating elementis located in each ink channel upstream from a nozzle so that thepiezoelectric oscillations propel ink through the nozzle. After the hotmelt ink is applied to the substrate, the ink is resolidified byfreezing on the substrate.

Each of these types of known ink jets, however, has a number ofadvantages and disadvantages. One advantage of thermal ink jets is theircompact design for the integrated electronics section of the printhead.Thermal ink jets are disadvantageous in that the thermal ink has atendency to soak into a plain paper medium. This blurs the print orthins out the print locally thereby adversely affecting print quality.Problems have been encountered with thermal ink jets in attempting torid the ink of moisture fast enough so that the ink does not soak into aplain paper medium. This is particularly true when printing with color.Therefore, usually when printing with thermal ink, one needed to usecoated papers, which are more expensive than plain paper.

One advantage of a hot melt ink jet is its ability to print on plainpaper since the hot melt ink quickly solidifies as it cools and, sinceit is waxy in nature it does not normally soak into a paper medium.However, hot melt ink jets can be cumbersome in structure and in design,that is, the associated integrated electronics of a thermal ink jet headare considerably more compact than those of a hot melt ink jet head.

In addition, U.S. Pat. No. 4,751,528, the disclosure of which is totallyincorporated herein by reference, discloses a hot melt ink jet systemwhich includes a temperature-controlled platen provided with a heaterand a thermoelectric cooler electrically connected to a heat pump and atemperature control unit for controlling the operation of the heater andthe heat pump to maintain the platen temperature at a desired level. Theapparatus also includes a second thermoelectric cooler to solidify hotmelt ink in a selected zone more rapidly to avoid offset by a pinch rollcoming in contact with the surface of the substrate to which hot meltink has been applied. An airtight enclosure surrounding the platen isconnected to a vacuum pump and has slits adjacent to the platen to holdthe substrate in thermal contact with the platen.

Further, U.S. Pat. No. 4,791,439, the disclosure of which is totallyincorporated by reference, discloses an apparatus for use with hot meltinks having an integrally connected ink jet head and reservoir system,the reservoir system including a highly efficient heat conducting plateinserted within an essentially nonheat conducting reservoir housing. Thereservoir system has a sloping flow path between an inlet position and asump from which ink is drawn to the head, and includes a plurality ofvanes situated upon the plate for rapid heat transfer.

U.S. Pat. No. 5,006,170 and U.S. Pat. No. 5,122,187, the disclosures ofeach of which are totally incorporated herein by reference, disclose hotmelt ink compositions suitable for ink jet printing which comprise acolorant, a binder, and a propellant such as hydrazine, cyclic amines,ureas, carboxylic acids, sulfonic acids, aldehydes, ketones,hydrocarbons, esters, phenols, amides, imides, halocarbons, and thelike. The inks of the present invention are dissimilar than theaforementioned '179 and '187, in that, for example, the inventionvehicle selected displays a viscosity of from about 1 to about 20, andpreferably 5 centipoise when heated to a temperature of from about 120°C. to about 165° C., such that acoustic energy in the printhead caneject an ink droplet onto paper. Additionally, the vehicles of thepresent invention display softening points of from about 50° C. to about100° C. and the invention vehicles, especially the oxazolinederivatives, are not disclosed in this prior art.

U.S. Pat. No. 5,041,161, the disclosure of which is totally incorporatedherein by reference, discloses an ink jet ink which is semi-solid atroom temperature. The ink combines the advantageous properties ofthermal phase inks and liquid inks. The inks comprise vehicles, such asglyceryl esters, polyoxyethylene esters, waxes, fatty acids, andmixtures thereof, which are semi-solid at temperatures between 20° C.and 45° C. The ink is impulse jetted at an elevated temperature in therange of about 45° C. to about 110° C., at which temperature the ink hasa viscosity of about 10 to 15 centipoise. The inks also contain 0.1 to30 weight percent of a colorant system.

U.S. Pat. No. 4,853,036 and U.S. Pat. No. 5,124,718 disclose an ink forink jet recording which comprises a liquid composition essentiallycomprising a coloring matter, a volatile solvent having a vapor pressureof 1 millimeter Hg or more at 25° C., and a material being solid at roomtemperature and having a molecular weight of 300 or more, and preparedso as to satisfy the formula B₁ /A₁ ≧3, assuming viscosity as A₁ cP at25° C., measured when the content of the solid material in thecomposition is 10 percent by weight, and assuming viscosity as B₁ cP at25° C., measured when the content of the solid material in thecomposition is 30 percent by weight. An ink jet recording process usingthe ink is also disclosed.

Oxazolines are known, as illustrated by R. H Wiley and L. L. Bennett inChemical Reviews, volume 44, pages 447 to 476 (1949), the disclosure ofwhich is totally incorporated herein by reference. Furthermore,oxazoline derivatives as being the major product from the reaction of anorganic acid and amino alcohol is also known, such as disclosed by A. I.Meyers and D. L. Temple in the Journal of the Chemical Society, volume92, page 6644 (1970), the disclosure of which is totally incorporatedherein by reference.

While the known compositions and processes may be suitable for theirintended purposes, a need remains for acoustic hot melt ink compositionssuitable for thermal ink jet printing. In addition, there is a need forhot melt ink compositions which are compatible with a wide variety ofplain papers. Further, there is a need for hot melt ink compositionswhich generate high quality, waterfast images on plain papers. There isalso a need for hot melt ink jet ink compositions which generate highquality, fast-drying images on a wide variety of plain papers at lowcost with high quality text and high quality graphics. Further, there isa need for hot melt ink jet ink compositions which exhibit minimalfeathering. Additionally, there is a need for hot melt ink jet inkcompositions which exhibit minimal intercolor bleed. There is also aneed for hot melt ink jet ink compositions which exhibit excellent imagepermanence. Further, there is a need for hot melt ink jet inkcompositions which are suitable for use in acoustic ink jet printingprocesses. Furthermore, there is a need for hot ink compositionssuitable for ink jet printing processes wherein the substrate is heatedprior to printing, and is cooled to ambient temperature subsequent toprinting (also known as heat and delay printing processes). There isalso a need for ink compositions suitable for ink jet printing whereinhigh optical densities can be achieved with relatively low dyeconcentrations. A need also remains for ink compositions suitable forink jet printing wherein curling of the substrate, such as paper,subsequent to printing is minimized, or avoided. These and other needsand advantages are achievable with the inks of the present invention inembodiments thereof.

SUMMARY OF THE INVENTION

Examples of objects of the present invention include, for example:

It is an object of the present invention to provide hot melt inkcompositions with many of the advantages illustrated herein.

It is another object of the present invention to provide hot melt inkcompositions suitable for acoustic ink jet printing.

It is yet another object of the present invention to provide hot meltink compositions which are compatible with a wide variety of plainpapers, and wherein in embodiments the ink possesses a low viscosity offrom 1 to about 5 centipoise at temperatures of from about 120° to about145° C.

It is still another object of the present invention to provide hot meltink compositions which generate high quality images on plain papers.

Another object of the present invention is to provide hot melt ink jetink compositions which are comprised of a colorant, preferably a dye,and vehicle comprised of an oxazoline or benzoxazoline as the majorcomponent and optionally an amide and/or amino ester as the minor, forexample in embodiments less than 30 weight percent, components, andwherein in embodiments the inks possess a low viscosity of, for example,1 to 5 at 120° to about 150° C.

Yet another object of the present invention is to provide hot ink jetink compositions which exhibit low viscosity of from about 1 to about 10centipoise at a temperature of from about 120° C. to about 150° C.

Still another object of the present invention is to provide hot melt inkjet ink compositions which exhibit high projection efficiency.

It is another object of the present invention to provide hot melt inkjet ink compositions which exhibit excellent image permanence.

It is yet another object of the present invention to provide hot ink jetink compositions that contain no water and which are suitable for use inacoustic ink jet printing processes.

It is still another object of the present invention to provide hot inkcompositions that contain no water and that are suitable for ink jetprinting processes wherein the substrate is heated prior to printing andis cooled to ambient temperature subsequent to printing (also known asheat and delay printing processes).

Another object of the present invention is to provide ink compositionssuitable for ink jet printing wherein high optical densities can beachieved with relatively low dye concentrations.

Yet another object of the present invention is to provide solvent freehot melt ink compositions suitable for ink jet printing wherein curlingof the substrate subsequent to printing is minimized.

Another object of the present invention resides in the provision of hotmelt inks wherein the viscosity of the ink is from about 1 centipoise toabout 10 centipoise at, for example, the jetting temperature which canbe from about 120° C. to about 180° C., and preferably from about 120°C. to about 145° C. thereby enabling excellent jetting at reasonablepower levels.

Further, in another object of the present invention there are providedhot melt inks with no water and a vehicle comprised of the reactionproduct of an organic acid and amino alcohol such as an oxazolinesvehicle (I), and a colorant such as a dye, and wherein the ink canoptionally further include an amino ester (III) or amide (II).

Additionally, in another object of the present invention there areprovided hot melt inks with no water or solvent for ink printing methodsand apparatuses, and wherein a number of the advantages as illustratedherein are achievable.

These and other objects of the present invention in embodiments thereofcan be achieved by providing an ink composition comprised of a colorantand a vehicle comprised of an oxazoline as the major constituent, andwhich ink possesses a viscosity of from about 1 centipoise to about 10centipoise at a temperature of from about 120° C. to about 150° C.; andan ink composition comprised of a colorant and an vehicle derived froman organic acid and amino alcohol, and which ink possesses a viscosityof from about 1 centipoise to about 5 centipoise at a temperature offrom about 140° C. to about 165° C., and which ink contains optionalknown ink additives.

DETAILED DESCRIPTION OF THE INVENTION

In embodiments, the ink compositions of the present invention comprisefrom about 3 to about 15 percent by weight of dye or pigment, and about85 to about 97 percent by weight of a vehicle. The vehicle is comprisedof from about 65 to about 100 percent by weight of an oxazoline (I) asthe major constituent, and of from about 0 to about 35 percent by weightof a mixture of an amide (II), and/or an amino ester (III).

Embodiments of the present invention include an ink compositioncomprised of a dye and a vehicle comprised of the reaction product of anorganic acid, such as stearic acid, and an amino alcohol, such as2-aminoethanol, and which product can be obtained by heating thereactants at elevated temperatures, such as from about 160° to about180° C., optionally in the presence of a condensation catalyst such asbutylstannoic acid or sulfuric acid. During the reaction, water isformed as the byproduct and removed via a distillation apparatus. Theresulting product is identified by nuclear magnetic resonance (NMR) andinfrared (IR) spectroscopy to be in embodiments a mixture of anoxazoline as the major product, for example about 65 to 100 percent byweight in embodiments, and further characterized by isolating theoxazoline compound by recrystallization using an appropriate solvent ormixture of solvents, such as dichloromethane, ethylacetate, methanol,toluene, hexane and the like, or by isolating the oxazoline usingchromatographic separation with silica or alumina and appropriate knownsolvents. The minor constituents, for example about 0 to about 35 weightpercent of the reaction product, are usually the amide (II) adduct ofthe organic acid and amino alcohol, or the amino ester (III) product.These latter two products (II) and (III) can also be isolated throughchromatographic separation and identified by NMR and/or IR spectroscopy.The oxazoline compound is preferred as the ink vehicle primarily becauseof its low viscosity properties. The amide or amino ester derivativesdisplay slightly higher viscosity, most likely due to the presence ofH-bonding through the amide or amine moieties. Although the oxazolinecan be isolated and utilized as the ink vehicle, it is preferable not toisolate the reaction product mixture primarily because of the highercost associated with its isolation. It is preferable in embodiments thatthe reaction be optimized to obtain a reaction product wherein theoxazoline content is high, such as from about 65 to 100 percent byweight of the product, and preferably from about 85 to about 97 percentof the product. Furthermore, the use of solvent for the reaction isavoided primarily for cost reduction purposes.

Examples of organic acids utilized in preparing the vehicle includeacetic acid, propanoic acid, butanoic acid, pentanoic acid, hexanoicacid, heptanoic acid, octanoic acid, decanoic acid, dodecanoic acid,tridecanoic acid, lauric acid, stearic acid, mixtures thereof, and thelike, and which acid is utilized in an effective amount of, for example,from about 25 to about 75 percent by weight of the reaction mixture.

Examples of amino alcohols selected for the generation of the vehiclesinclude 2-aminoethanol, 2-aminopropanol, 2- aminobutanol,2-aminohexanol, 2-methyl-2-aminoethanol, 2-methyl-2-aminoethanol,2-methyl-2-aminopropanol, 2-ethyl-2-aminoethanol,2-ethyl-2-aminopropanol, 1-amino-2-propanol, 1-amino-2-butanol,1-amino-2-pentanol, 3-amino-2-butanol, 2-amino-1,3-propanediol,2-amino-2-ethyl-1,3-propanediol, 3-amino-1,2-propanediol,tris-(hydroxymethyl)aminomethane, mixtures thereof, and the like, andwhich alcohol is selected in an effective amount of, for example, fromabout 10 to about 50 percent by weight of the reaction mixture.

Examples of condensation catalysts that can be utilized include sulfuricacid, phosphoric acid, zinc chloride, magnesium chloride, zinc acetate,magnesium acetate, dibutyl tin laurate, butylstannoic acid, mixturesthereof, and the like, and which catalyst is selected in an effectiveamount of, for example, from about 0.01 to about 1 percent by weight ofthe reaction mixture.

In one embodiment of the present invention, a vehicle derived from 1mole of stearic acid and 1 mole of 1-amino-2-propanol is prepared bycharging a 1 liter Parr reactor equipped with a distillation apparatusand mechanical stirrer with about 284 grams of stearic acid, 75 grams of1-amino-2-propanol and 0.3 gram of butylstannoic acid. The mixture isthen heated with stirring to about 160° C., and wherein water iscollected in the distillation receiver flask. The mixture is then heatedto about 180° C. over a two hour period and the pressure is thendecreased from atmospheric pressure to about 1 millimeter Hg over a 1hour period. During the entire reaction time, about 31 grams of waterare collected. The reaction mixture is then pressurized to atmosphericpressure and the product cooled to room temperature, about 25° C. Theproduct was then characterized and was comprised of a mixture of about95 percent by weight of 2-stearyl-4-methyl-oxazoline (structure I,wherein R₁ is stearyl group, R₂, R₃, and R₄ are hydrogen, and R₅ is amethyl group), and about 5 percent of N-(2-hydroxyethyl)-stearamide(structure II, wherein R₁ is stearyl, R₂, R₃, and R₄ are hydrogen, andR₅ is methyl, and which product has a melting point of about 82° C. asmeasured by the ELECTROTHERMAL® melting point apparatus, and wherein thestructure or formula was determined by both proton and carbon-13 NuclearMagnetic Resonance. The viscosity of the vehicle product can then bemeasured to be about 4 centipoise at a temperature of about 140° C.

Embodiments of the present invention include an ink composition with acertain vehicle of an oxazoline I or benzoxazoline Ia as represented bythe following Formulas ##STR2## wherein R₁ is an alkyl group of fromabout 1 to about 55 carbon atoms, R₂, R₃, R₄ and R₅ are alkyl, an alkylalcohol or an alkyl ester, each alkyl containing from about 1 to about55 carbon atoms; wherein R₂, R₃, R₄ and R₅ are the alkyl alcohol--(CH₂)_(n) --OH, wherein n is an integer of from about 1 to about 6, orwherein R₂, R₃, R₄ and R₅ are the alkyl ester (CH₂)n-O₂ C--(CH₂)_(m)CH₃, wherein n is an integer of from about 1 to about 6, and m is aninteger of from about 1 to about 53; wherein the amide is present and isrepresented by the following Formulas II or IIa ##STR3## wherein R₁ isan alkyl group of from about 1 to about 55 carbon atoms, R₂, R₃, R₄ andR₅ are an alkyl, an alkyl alcohol or an alkyl ester group, each alkylcontaining from about 1 to about 55 carbon atoms; wherein the aminoester is present, and is represented by the following Formula III##STR4## wherein R₁ is an alkyl group of from about 1 to about 55 carbonatoms, R₂, R₃, R₄ and R₅ are alkyl, an alkyl alcohol or an alkyl ester,each alkyl containing from about 1 to about 55 carbon atoms; a printingprocess which comprises incorporating into an acoustic ink jet printeran ink comprised of a colorant and an oxazoline component vehicle, andwhich ink possesses a viscosity of from about 1 centipoise to about 25centipoise at a temperature of from about 125° C. to about 185° C.; anink composition comprised of a colorant and an oxazoline vehicle, andwhich ink possesses a viscosity of from about 1 centipoise to about 25centipoise at a temperature of from about 125° C. to about 185° C.; andan ink composition comprised of a colorant and a benzoxazoline vehicle,and which ink possesses a viscosity of from about 1 centipoise to about25 centipoise at a temperature of from about 125° C. to about 185° C.

In another embodiment of the present invention, a vehicle derived from 2moles of stearic acid and 1 mole of 2-amino-2-ethyl-1,3-propanediol isprepared by charging a 1 liter Parr reactor equipped with a distillationapparatus and mechanical stirrer with about 284 grams of stearic acid,60 grams of 2-amino-2-ethyl-1,3-propanediol and 0.5 gram ofbutylstannoic acid. The mixture is then heated with stirring to about160° C., and wherein water is collected in the distillation receiverflask. The mixture is then heated to about 180° C. over a two hourperiod, and the pressure is then decreased from atmospheric pressure toabout 1 millimeter Hg over a 1 hour period. During the entire reactiontime, about 31 grams of water were collected. The reaction mixture isthen pressurized to atmospheric pressure and the product cooled to roomtemperature. The product is then characterized and has a melting pointof about 45° C. as measured by the ELECTROTHERMAL® melting pointapparatus, and the structure thereof was determined by Nuclear MagneticResonance indicating that the product is comprised of a mixture of about93 percent by weight of 2-stearyl-5-ethyl-5-methoxystearate-oxazoline(illustrated as structure IV), about 7 percent by weight of a mixture ofN'-(2-methoxystearate-butane)stearamide (illustrated as structure V) and2-stearyl-5-ethyl-5-methanol-oxazoline (illustrated as structure VI).The viscosity was then measured to be about 5.4 centipoise at atemperature of about 120° C.

A reaction sequence summary follows. ##STR5##

Oxazoline examples include2-stearyl-5-ethyl-5-methoxystearate-oxazoline,2-stearyl-5-ethyl-5-hydroxymethyl-oxazoline,2-stearyl-4-ethyl-oxazoline, 2-stearyl-4-methoxystearate-oxazoline,2-stearyl-4-hydroxymethyl-oxazoline,2-stearyl-4-hydroxymethyl-bis-5,5-(methoxystearate)-oxazoline,2-stearyl-5-hydroxymethyl-5-(methoxystearate)-oxazoline, mixturesthereof, and the like, as illustrated herein.

Examples of colorants, preferably dyes selected for the inks of thepresent invention, are known, reference the Color Index, and includethose as illustrated in U.S. Pat. No. 5,310,887, the disclosure of whichis totally incorporated herein by reference, and, for example, ResorcinCrystal Violet, Orasol Black RL or Intraplast Black RL/Solvent Black 29,Lapranol Black BR, Savinyl Black RLS, Orasol Black RLP, Neozapon BlackX57; solvent yellow dyes inclusive of Savinyl Yellow 2 RLS, SavinylYellow RLSN, Intraplast Yellow 2GLN, Neozapon Yellow 081, NeozaponYellow 141, Levaderm Lemon Yellow, Zapon Fast Yellow CGR, Aizen FastYellow CGNH, Zapon Yellow 100, Zapon Yellow 157, and Savinyl Yellow RLS;Neopan Yellow 075; Neopan blue; REGAL 3300 carbon black; SunbrightYellow; Sunbright Rubine, Sunchem Yellow, Sunchem Blue, Sunchem Rubineavailable from Sun Chemical Corporation; magenta dyes such as NeozaponRed 492, Direct Brilliant Pink B, Savinyl Pink 6 BLS, Savinyl Red 3 BLS,Orasol Red 2 BL, Intraplast Red G (Orasol Red), Savinyl Red BLSN,Savinyl Scarlet RLS, Savinyl Fire Red 3GLS, and Zapon Red 335; cyan dyessuch as Orasol Blue 2 GLN, Neozapon Blue 807, Savinyl Blue RLS, SavinylBlue GLS, Orasol Blue GN, and Losol Blue; brown dyes inclusive of ZaponBrown 187 and Savinyl Brown GLS, Solvent Green 3, Sudan Black B, CeresBlue 2V, Liquid Oil Jet Black, Macrolex Red G Gram, Macrolex Yellow 3G,Victoria Blue R, available from Bayer AG, Leverkusen, Germany, MorfastBlue 100, Morfast Red 104, and Morfast Red 100, available from MortonInternational Specialty Chemicals Group, Chicago, Ill.; mixturesthereof; and the like with preferred dyes in embodiments includingReactint Black 57AB, Reactint Black X40LV, Reactint Blue 17AB, ReactintBlue X3LV, Reactint Blue X19, Reactint Red X26B-50, Reactint Red X520,Reactint Violet X80LT, Reactint Orange X38, and Reactint Yellow X15, allavailable from Milliken Chemicals. Typically, the dye is present in theink in an amount of from about 0.01 to about 10 percent by weight,preferably from about 0.05 to about 4 percent by weight, and morepreferably from about 0.1 to about 3 percent by weight, although theamount can be outside these ranges.

The inks of the present invention can contain a colorant comprised of amixture of dyes and pigments.

Optional ink additives include biocides such as DOWICIL 150™, 200™, and75™, benzoate salts, sorbate salts, and the like, present in effectiveamounts, such as for example an amount of from about 0.0001 to about 4percent by weight, and preferably from about 0.01 to about 2.0 percentby weight; pH controlling agents such as acids, or bases, phosphatesalts, carboxylates salts, sulfite salts, amine salts, and the like,present in an amount of from 0 to about 1 percent by weight andpreferably from about 0.01 to about 1 percent by weight, or the like.

The inks of the present invention are particularly suitable for printingprocesses wherein the substrate, such as paper, transparency material,or the like, is heated during the printing process to facilitateformation of the liquid crystalline phase within the ink. Preferably,the substrate is heated to the highest temperature possible to enablethe most rapid possible ink drying without damaging the substrate. Whentransparency substrates are employed, temperatures typically are limitedto a maximum of about 100° C. to about 110° C., since the polyestertypically employed as the base sheet in transparency sheets tends todeform at higher temperatures. Specially formulated transparencies andpaper substrates can, however, tolerate higher temperatures, frequentlybeing suitable for exposure to temperatures of 150° C. or even 200° C.in some instances. Typical heating temperatures are from about 40° C. toabout 140° C., and preferably from about 60° C. to about 95° C.,although the temperature can be outside these ranges.

The inks of the present invention can be prepared by various suitablemethods. For example, the inks can be prepared by gently stirring orshaking the individual components, such as melt mixing the vehicle witha colorant at a temperature of from about 90° C. to about 130° C.,followed by cooling to about 25° C.

The inks of the present invention are particularly suitable for use inacoustic ink jet printing processes. In acoustic ink jet printing,reference the patents recited here, the disclosures of which have beentotally incorporated herein by reference, an acoustic beam exerts aradiation pressure against objects upon which it impinges. Thus, when anacoustic beam impinges on a free surface of the ink of a pool of liquidfrom beneath, the radiation pressure which it exerts against the surfaceof the pool may reach a sufficiently high level to release individualdroplets of liquid from the pool, despite the restraining force ofsurface tension. Focusing the beam on or near the surface of the poolintensifies the radiation pressure it exerts for a given amount of inputpower, reference for example IBM Technical Disclosure Bulletin, Vol. 16,No. 4, September 1973, pages 1168 to 1170, the disclosure of which istotally incorporated herein by reference. Acoustic ink printerstypically comprise one or more acoustic radiators for illuminating thefree surface of a pool of liquid ink with respective acoustic beams.Each of these beams usually is brought to focus at or near the surfaceof the reservoir (i.e., the liquid/air interface). Furthermore, printingconventionally is performed by independently modulating the excitationof the acoustic radiators in accordance with the input data samples forthe image that is to be printed. This modulation enables the radiationpressure, which each of the beams exerts against the free ink surface,to make brief, controlled excursions to a sufficiently high pressurelevel for overcoming the restraining force of surface tension. That, inturn, causes individual droplets of ink to be ejected from the free inksurface on demand at an adequate velocity to cause them to deposit in animage configuration on a nearby recording medium. The acoustic beam maybe intensity modulated or focused/defocused to control the ejectiontiming, or an external source may be used to extract droplets from theacoustically excited liquid on the surface of the pool on demand.Regardless of the timing mechanism employed, the size of the ejecteddroplets is determined by the waist diameter of the focused acousticbeam. Acoustic ink printing is attractive because it does not requirethe nozzles or the small ejection orifices which have caused many of thereliability and pixel placement accuracy problems that conventional dropon demand and continuous stream ink jet printers have suffered. The sizeof the ejection orifice is a critical design parameter of an ink jetbecause it determines the size of the droplets of ink that the jetejects. As a result, the size of the ejection orifice cannot beincreased without sacrificing resolution. Acoustic printing hasincreased intrinsic reliability since usually there are no nozzles toclog. Furthermore, small ejection orifices are avoided, so acousticprinting can be performed with a greater variety of inks thanconventional ink jet printing, including inks having higher viscositiesand inks containing pigments and other particulate components. Acousticink printers embodying printheads comprising acoustically illuminatedspherical focusing lenses can print precisely positioned pixels (pictureelements) at resolutions which are sufficient for high quality printingof relatively complex images. It has also been determined that the sizeof the individual pixels printed by such a printer can be varied over asignificant range during operation, thereby accommodating, for example,the printing of variably shaded images. Furthermore, the known dropletejector technology can be adapted to a variety of printheadconfigurations, including (1) single ejector embodiments for raster scanprinting, (2) matrix configured ejector arrays for matrix printing, and(3) several different types of pagewidth ejector arrays, ranging from(i) single row, sparse arrays for hybrid forms of parallel/serialprinting to (ii) multiple row staggered arrays with individual ejectorsfor each of the pixel positions or addresses within a pagewidth imagefield (i.e., single ejector/pixel/line) for ordinary line printing. Inkssuitable for acoustic ink jet printing typically are liquid at ambienttemperatures (i.e., about 25° C.), however, in other embodiments the inkis in a solid state at ambient temperatures and provision is made forliquefying the ink by heating or any other suitable method prior tointroduction of the ink into the printhead. Images of two or more colorscan be generated by several methods, including by processes wherein asingle printhead launches acoustic waves into pools of different coloredinks. Further information regarding acoustic ink jet printing apparatusand processes is disclosed in, for example, U.S. Pat. No. 4,308,547,U.S. Pat. No. 4,697,195, U.S. Pat. No. 5,028,937, U.S. Pat. No.5,041,849, U.S. Pat. No. 4,751,529, U.S. Pat. No. 4,751,530, U.S. Pat.No. 4,751,534, U.S. Pat. No. 4,801,953, and U.S. Pat. No. 4,797,693, thedisclosures of each of which are totally incorporated herein byreference. The use of focused acoustic beams to eject droplets ofcontrolled diameter and velocity from a free-liquid surface is alsodescribed in J. Appl. Phys., vol. 65, no. 9 (1 May 1989) and referencestherein, the disclosure of which is totally incorporated herein byreference.

Specific embodiments of the invention will now be described in detail.These Examples are intended to be illustrative, and the invention is notlimited to the materials, conditions, or process parameters set forth inthese embodiments. All parts and percentages are by weight unlessotherwise indicated.

EXAMPLE I

An ink vehicle derived from the condensation product of one mole ofstearic acid and one mole of 1-amino-2-propanol using butylstannoic acidas the catalyst was prepared as follows.

A 1 liter Parr reactor equipped with a distillation apparatus andmechanical stirrer was charged with about 284 grams of stearic acid, 75grams of 1-amino-2-propanol and 0.3 gram of butylstannoic acid. Themixture was then heated with stirring to about 160° C., and whereinwater was collected in the distillation receiver flask. The mixture wasthen heated to about 180° C. over a two hour period and the pressure wasthen decreased from atmospheric pressure to about 1 millimeter Hg over a1 hour period. During the entire reaction time, about 31 grams of waterwere collected. The reaction mixture was then pressurized to atmosphericpressure and the product cooled to room temperature. The productresulting was then characterized to have a melting point of about 70° C.as measured by a melting point apparatus, and the product was identifiedby Nuclear Magnetic Resonance to be comprised of a mixture of about 93percent by weight of 2-stearyl-4-methyl-oxazoline (structure I, whereinR₁ is stearyl group, R₂, R₃, and R₄ are hydrogen, and R₅ is a methylgroup), and about 7 percent of N-(2-hydroxyethyl)-stearamide (structureII, wherein R₁ is a stearyl group, R₂, R₃, and R₄ are hydrogen, and R₅is a methyl group). The viscosity, penetration and acoustic loss werethen measured and are reported in Table 1.

EXAMPLE II

An ink vehicle derived from the condensation product of one mole ofstearic acid and one mole of 2-amino-2-ethyl-1,3-propanediol usingbutylstannoic acid as the catalyst was prepared as follows.

A 1 liter Parr reactor equipped with a distillation apparatus andmechanical stirrer was charged with about 284 grams of stearic acid, 60grams of 2-amino-2-ethyl-1,3-propanediol and 0.49 gram of butylstannoicacid. The mixture was then heated with stirring to about 160° C., andwherein water was collected in the distillation receiver flask. Theresulting mixture was then heated to about 180° C. over a two hourperiod and the pressure was then decreased from atmospheric pressure toabout 1 millimeter Hg over a 1 hour period. During the entire reactiontime, about 30 grams of water were collected. The reaction mixture wasthen pressurized to atmospheric pressure and the product cooled to roomtemperature. The product was characterized to have a melting point ofabout 45° C. as measured by the melting point apparatus, and the productwas identified by Nuclear Magnetic Resonance to be comprised of amixture of about 88 percent by weight of2-stearyl-5-ethyl-5-methoxystearate-oxazoline (structure I, wherein R₁is a stearyl group, R₂ is an ethyl group, R₃ is a CH₂ --O--C(O)--(CH₂)₁₆CH₃ group, and R₄ and R₅ are both hydrogen atoms), about 8 percent byweight of 2-stearyl-5-ethyl-5-methanol-oxazoline (structure I, whereinR₁ is a stearyl group, R₂ is an ethyl group, R₃ is CH₂ --O--H, and R₄and R₅ are both hydrogen), and about 6 percent by weight ofN'-(2-methoxystearate-butane)-stearamide (structure III, wherein R₁ is astearyl group, R₂ is an ethyl group, R₃ is CH₂ --O--C(O)--(CH₂)₁₆ CH₃,and R₄ and R₅ are both hydrogen atoms). The viscosity, penetration pointand acoustic loss were then measured and are reported in Table 1.

EXAMPLE III

An ink vehicle derived from the condensation product of one mole ofstearic acid and 0.5 mole of 2-amino-2-ethyl-1,3-propanediol usingbutylstannoic acid as the catalyst was prepared as follows.

A 1 liter Parr reactor equipped with a distillation apparatus andmechanical stirrer was charged with about 284 grams of stearic acid, 120grams of 2-amino-2-ethyl-1,3-propanediol and 0.25 gram of butylstannoicacid. The mixture resulting was then heated with stirring to about 160°C., and wherein water was collected in the distillation receiver flask.The mixture was then heated to about 180° C. over a two hour period andthe pressure was then decreased from atmospheric pressure to about 1millimeter Hg over a 1 hour period. During the entire reaction time,about 31 grams of water were collected. The reaction mixture was thenpressurized to atmospheric pressure and the product cooled to roomtemperature. The product was characterized to have a melting point ofabout 35° C. as measured by a melting point apparatus, and the productwas identified by Nuclear Magnetic Resonance to be comprised of amixture of about 95 percent by weight of2-stearyl-5-ethyl-5-methanol-oxazoline (structure I, wherein R₁ is astearyl group, R₂ is an ethyl group, R₃ is a CH₂ --O--H group, and R₄and R₅ are both hydrogen atoms), and about 5 percent by weight of2-(stearylacrylamido)-2-ethyl-1,3-propanediol (structure II, wherein R₁is a stearyl group, R₂ is an ethyl group, R₃ is a CH₂ --O--H group, andR₄ and R₅ are both hydrogen atoms). The viscosity, penetration point andacoustic loss were then measured and are reported in Table 1.

EXAMPLE IV

An ink vehicle derived from the condensation product of one mole ofstearic acid and 0.5 mole of 3-amino-1,2-propanediol using butylstannoicacid as the catalyst was prepared as follows.

A 1 liter Parr reactor equipped with a distillation apparatus andmechanical stirrer was charged with about 284 grams of stearic acid,45.5 grams of 3-amino-1,2-propanediol and 0.2 gram of butylstannoicacid. The mixture was then heated with stirring to about 160° C., andwater was collected in the distillation receiver flask. The mixture wasthen heated to about 180° C. over a two hour period and the pressure wasthen decreased from atmospheric pressure to about 1 millimeter Hg over a1 hour period. During the entire reaction time, about 31 grams of waterwere collected. The reaction mixture was then pressurized to atmosphericpressure and the product cooled to room temperature. The product wasthen characterized to have a broad melting point of about 85° to about92° C. as measured by the melting point apparatus, and the product wasidentified by Nuclear Magnetic Resonance to be comprised of a mixture ofabout 75 percent by weight of 2-stearyl-4-methoxystearate-oxazoline(structure I, wherein R₁ is a stearyl group, R₂, R₃ and R₄ are hydrogenatoms and R₅ is a CH₂ --O--C(O)--(CH₂)₁₆ CH₃ group), about 25 percent byweight of a mixture of an amide (illustrated as structure II, wherein R₁is a stearyl group, R₂, R₃ and R₄ are hydrogen atoms and R₅ is a CH₂--O--C(O)--(CH₂)₁₆ CH₃ group) and an amino-ester (structure III, whereinR₁ is a stearyl group, R₂, R₃ and R₄ are hydrogen atoms and R₅ is a CH₂--O--C(O)--(CH₂)₁₆ CH₃ group). The viscosity, penetration point andacoustic loss were then measured and are reported in Table 1.

EXAMPLE V

An ink vehicle derived from the condensation product of one mole ofstearic acid and one mole of 3-amino-1,2-propanediol using butylstannoicacid as the catalyst was prepared as follows.

A 1 liter Parr reactor equipped with a distillation apparatus andmechanical stirrer was charged with about 284 grams of stearic acid, 91grams of 3-amino-1,2-propanediol and 0.3 gram of butylstannoic acid. Themixture was then heated with stirring to about 160° C., and water wascollected in the distillation receiver flask. The mixture was thenheated to about 180° C. over a two hour period and the pressure was thendecreased from atmospheric pressure to about 1 millimeter Hg over a 1hour period. During the entire reaction time, about 31 grams of waterwere collected. The reaction mixture was then pressurized to atmosphericpressure and the product cooled to room temperature. The product wascharacterized to have a melting point of about 102° C. as measured bythe melting point apparatus, and the structure product was identified byNuclear Magnetic Resonance to be comprised of a mixture of about 96percent by weight of 2-stearyl-4-methanol-oxazoline (structure I,wherein R₁ is a stearyl group, R₂, R₃, and R₄ are hydrogen atoms, and R₅is a methanol group), and about 4 percent by weight of an amide(structure II, wherein R₁ is a stearyl group, R₂, R₃, and R₄ arehydrogen atoms and R₅ is a methanol group). The viscosity, penetrationpoint and acoustic loss were then measured and are reported in Table 1.

EXAMPLE VI

An ink vehicle derived from the condensation product of one mole ofstearic acid and 0.33 mole of tris(hydroxymethyl) aminomethane usingbutylstannoic acid as the catalyst was prepared as follows.

A 1 liter Parr reactor equipped with a distillation apparatus andmechanical stirrer with about 284 grams of stearic acid, 41 grams oftris(hydroxymethyl) aminomethane and 0.3 gram of butylstannoic acid. Themixture was then heated with stirring to about 170° C., and water wascollected in the distillation receiver flask. The mixture was thenheated to about 180° C. over a two hour period and the pressure was thendecreased from atmospheric pressure to about 1 millimeter Hg over a 1hour period. During the entire reaction time, about 30 grams of waterwere collected. The reaction mixture was then pressurized to atmosphericpressure and the product cooled to room temperature. The product wasthen characterized to have a melting point of about 75° to 80° C. asmeasured by the melting point apparatus, and the product was identifiedby Nuclear Magnetic Resonance to be comprised of a mixture of about 95percent by weight of 2-stearyl-bis-5,5-(methoxystearate)-oxazoline(structure I, wherein R₁ is a stearyl group, R₂ and R₃ are CH₂--O--C(O)--(CH₂)₁₆ CH₃ groups, and R₄ and R₅ are hydrogen groups), andabout 5 percent by weight of a mixture of an amide (structure I, whereinR₁ is a stearyl group, R₂ and R₃ are CH₂ --O--C(O)--(CH₂)₁₆ CH₃ groups,and R₄ and R₅ are hydrogen groups), and2-stearyl-bis-5-hydroxymethyl-5-(methoxystearate)-oxazoline (structureI, wherein R₁ is a stearyl group, R₂ is a methanol group, and R₃ is aCH₂ --O--C(O)--(CH₂)₁₆ CH₃ group, and R₄ and R₅ are hydrogen). Theviscosity, penetration point and acoustic loss were then measured andare reported in Table 1.

EXAMPLE VII

An ink vehicle derived from the condensation product of one mole ofstearic acid and 0.5 mole of tris(hydroxymethyl) aminomethane usingbutylstannoic acid as the catalyst was prepared as follows.

A 1 liter Parr reactor equipped with a distillation apparatus andmechanical stirrer with about 284 grams of stearic acid, 60.5 grams oftris(hydroxymethyl) aminomethane and 0.3 gram of butylstannoic acid. Themixture was then heated with stirring to about 170° C., and and waterwas collected in the distillation receiver flask. The mixture was thenheated to about 180° C. over a two hour period and the pressure was thendecreased from atmospheric pressure to about 1 millimeter Hg over a 1hour period. During the entire reaction time, about 30 grams of waterwere collected. The reaction mixture was then pressurized to atmosphericpressure and the product cooled to room temperature. The product wascharacterized to have a melting point of about 61° C. as measured by themelting point apparatus, and the product/structure was identified byNuclear Magnetic Resonance to be comprised of a mixture of about 95percent by weight of2-stearyl-bis-5-hydroxymethyl-5-(methoxystearate)-oxazoline (structureI, wherein R₁ is a stearyl group, R₂ is a methanol group, and R₃ is aCH₂ --O--C(O)--(CH₂)₁₆ CH₃ groups, and R₄ and R₅ are hydrogen groups),and about 5 percent by weight of an amide (structure II, wherein R₁ is astearyl group, R₂ is a methanol group, and R₃ is a CH₂--O--C(O)--(CH₂)₁₆ CH₃ group, and R₄ and R₅ are hydrogen). Theviscosity, penetration point and acoustic loss were then measured andare reported in Table 1.

                  TABLE 1                                                         ______________________________________                                                  Viscosity  Acoustic Loss                                                                            Penetration                                             mPa s      dB/mm      mm                                            Vehicle   (150° C.)                                                                         (150° C.)                                                                         (25° C.)                               ______________________________________                                        Example I 3.6        34.0       0.8                                           Example II                                                                              3.3        32.2       1.0                                           Example III                                                                             4.0        32.0       2.3                                           Example IV                                                                              4.8        44.7       0.95                                          Example V 13.7       48.5       0.6                                           Example VI                                                                              4.4        34.0       0.45                                          Example VII                                                                             4.4        35.6       0.65                                          ______________________________________                                    

EXAMPLE VIII

An ink vehicle derived from the condensation product of one mole ofstearic acid and one mole of 2-aminophenol using butylstannoic acid asthe catalyst was prepared as follows.

A 1 liter Parr reactor equipped with a distillation apparatus andmechanical stirrer with about 284 grams of stearic acid, 109 grams of2-aminophenol and 0.3 gram of butylstannoic acid. The mixture was thenheated with stirring to about 170° C., and wherein water was collectedin the distillation receiver flask. The mixture was then heated to about180° C. over a two hour period and the pressure was decreased fromatmospheric pressure to about 1 millimeter Hg over a 1 hour period.During the entire reaction time, about 30 grams of water were collected.The reaction mixture was then pressurized to atmospheric pressure andthe product cooled to room temperature. The product was characterized tohave a melting point of about 50° C. as measured by the melting pointapparatus, and the product was identified further by Nuclear MagneticResonance to be comprised of a mixture of about 77 percent by weight of2-stearylbenzoxazoline (structure Ia, wherein R₁ is a stearyl group, andR₂, R₃, R₄, and R₅ are all hydrogen atoms), about 23 percent by weightof a mixture of starting material and amide (structure IIa, wherein R₁is a stearyl group, and R₂, R₃, R₄, and R₅ are all hydrogen atoms).

Penetration, Acoustic Loss and Viscosity Measurements

The penetration was measured using a K.I.C. penetrometer available byNoran Inc., using the following procedure.

1. A test sample was melted to approximately 20° C. above its meltingpoint in an aluminum pan, with stirring to free any air bubbles.

2. The melted sample was then poured down a brass cylinder in a mannerthat a convex meniscus is formed. The brass cylinder, fitted at one endwith a removable brass cover, was located inside a block heater coverdown, and maintained in the molten state for one hour.

3. The sample and container were then cooled, inside the block heater,to 25° C. at a controlled rate, and left undisturbed for 24 hours at themeasuring temperature.

4. The cylinder was then removed off the block heater and reversed. Thebrass cover was removed and a smooth, flat surface was exposed. Thecontainer was then positioned on the penetrometer base with the smoothsurface up. A 100 gram weight is placed above the penetrometer needle,providing a total load of 150 gram for the needle and all attachments.The indicator assembly was then positioned to the "zero" position. Theindicator assembly was then adjusted until the tip of the needle nearlytouches the surface of the specimen. The movable assembly was locked inthis position.

5. By means of the slow adjustment, the needle was brought to just touchthe surface of the specimen. After 5 minutes, the needle shaft wasreleased and held free for 5 seconds. Then, the indicator shaft wasdepressed until it was stopped by the needle shaft, and the penetrationwas read from the indicator scale in units of millimeter.

The acoustic attenuation is measured with a custom made acoustic testfixture comprised of two transducers set on top of each other. Thebottom transducer is sitting on a translation stage so that it can bepositioned laterally towards the top of the transducer to provide amaximum signal. The space between the transducers is controlled by amechanism located on the bottom transducer. The top transducer isconnected to an oscilloscope where the amplitude of the acoustic signalis detected. The attenuation is measured as the sound loss across theink sample when the transducers are set apart by a predetermineddistance. Each transducer is fitted with a heat resistance and athermocouple coupled to a heat controller. The acoustic loss is thenmeasured using the following procedure:

1. The ink sample specimen is placed in between the transducers. Thetemperature is adjusted to a set temperature of 150° C. The sample isthen left undisturbed until it equilibrates to 150° C. for 5 minutes.

2. The two transducers are brought together in such a way that theacoustic signal on the oscilloscope is maximized. The amplitude and theposition of the signal are recorded.

3. The two transducers are separated by a distance varying from 25.4microns to 125.4 microns. Then, the amplitude and position of the signalare recorded. Each measurement is performed three times and threesamples of the same specimen are measured.

4. The attenuation in decibel per millimeter (dB/mm) is then calculatedby rationing the amplitude values obtained at different separationdistances.

The rheological characterization was performed using Carri-Med CSL-100controlled stress rheometer using a 4 centimeter, 2 degree cone andplate geometry. The measurement consisted of 5 consecutive shear ratesweeps, up to the maximum rate of 1,250 s⁻¹ and at a temperature of 100°C. to 180° C. increments. The infinite shear viscosity was then reportedat 150° C.

EXAMPLE IX TO EXAMPLE XV

Various ink compositions comprised of about 95 percent by weight ofvehicle and 5 percent by weight of colorant were prepared by melt mixingat 120° C. using a mechanical stirrer for a duration of 5 minutes. Thecolorants utilized were Neopan Yellow 075, Neopan Blue, both obtainedfrom BASF Corporation, black pigment REGAL 330® obtained from Cabot,Sunbright Rubine obtained from Sun Chemical Corporation, and ReactintBlack X57-AB obtained from Milliken Chemicals. The color properties andviscosity characteristics are reported in Table 2.

                  TABLE 2                                                         ______________________________________                                                                           Viscosity                                                                     mPa s                                      Vehicle     Vehicle    Colorant    (150° C.)                           ______________________________________                                        Example IX  Example VI Neopan Blue 5.1                                        Example X   Example II Neopan Yellow                                                                             4.7                                        Example XII Example VII                                                                              Neopan Yellow                                                                             4.9                                        Example XI  Example VI Regal 330   11.0                                       Example XIII                                                                              Example VI Sunbright Rubine                                                                          10.8                                       Example XIV Example VI Neopan Yellow                                                                             4.8                                        Example XV  Example VI R. Black X57A                                                                             4.2                                        ______________________________________                                    

Images developed with the above prepared inks in an acoustic ink jetprinter test fixture evidence, it is believed, excellent image qualityand the other advantages illustrated herein.

Other modifications of the present invention may occur to those ofordinary skill in the art subsequent to a review of the presentapplication, and these modifications, including equivalents thereof, areintended to be included within the scope of the present invention.

What is claimed is:
 1. An ink composition comprised of a colorant and avehicle component, and which vehicle component is comprised of thecondensation product of an organic acid and an amino alcohol, and amixture of an amide and an amino ester, and wherein said mixturecontains from about 1 to about 99 parts of said amide and from about 99parts to about 1 part of said ester.
 2. An ink in accordance with claim1 wherein said amide is represented by Formulas II, or IIa ##STR6##wherein R1 is an alkyl group of from about 1 to about 55 carbon atoms,R₂, R₃, R₄ and R₅ are an alkyl, an alkyl alcohol or an alkyl estergroup, each alkyl containing from about 1 to about 55 carbon atoms. 3.An ink in accordance with claim 2 wherein R₂, R₃, R₄ and R₅ are thealkyl alcohol --(CH₂)_(n) --OH wherein n is an integer of from about 1to about 6, or the alkyl ester --(CH₂)n-O₂ C--(CH₂)_(m) CH₃ wherein n isan integer of from about 1 to about 6, and m is an integer of from about1 to about
 53. 4. An ink in accordance with claim 1 wherein said aminoester is represented by Formula III ##STR7## wherein R₁ is an alkylgroup of from about 1 to about 55 carbon atoms, R₂, R₃, R₄ and R₅ arealkyl, an alkyl alcohol or an alkyl ester, each with from about 1 toabout 55 carbon atoms.
 5. An ink in accordance with claim 4 wherein R₁is an alkyl group of from about 1 to about 55 carbon atoms, R₂, R₃, R₄and R₅ are alkyl, an alkyl alcohol or an alkyl ester, each with fromabout 1 to about 55 carbon atoms.
 6. An ink in accordance with claim 1wherein said colorant is a dye.
 7. An ink in accordance with claim 1wherein said colorant is a pigment.
 8. An ink in accordance with claim 1wherein said colorant is comprised of mixtures of dyes and pigments. 9.An ink in accordance with claim 1 wherein said colorant is present in anamount of about 0.01 to about 10 percent by weight.
 10. An ink inaccordance with claim 1 wherein said colorant is present in an amount ofabout 1 to about 5 percent by weight.
 11. An ink in accordance withclaim 1 possessing a viscosity of about 1 to about 25 centipoise at atemperature of about 125° C. to about 185° C.
 12. An ink in accordancewith claim 1 possessing a viscosity of about 1 to about 10 centipoise ata temperature of about 120° C. to about 150° C.
 13. An ink in accordancewith claim 1 with about 85 to about 97 percent by weight of saidvehicle, and about 3 to about 15 percent by weight of said colorant. 14.An ink in accordance with claim 1 wherein said condensation product ispresent in an amount of from about 65 to about 99 weight percent, andsaid mixture of amide and amino ester is present in an amount of fromabout 1 to about 35 weight percent.
 15. A process which comprises (a)providing an acoustic ink printer having a pool of liquid ink with afree surface, and a printhead including at least one droplet ejector forradiating the free surface of said ink with focused acoustic radiationto eject individual droplets of ink therefrom on demand, said radiationbeing brought to focus with a finite waist diameter in a focal plane,and wherein said ink composition selected is comprised of a colorant,and a vehicle component, and which vehicle component is comprised of thecondensation product of an organic acid and an amino alcohol; and (b)causing droplets of said ink to be ejected onto a recording sheet in animagewise pattern at a temperature of from about 120° C. to about 185°C.
 16. A printing process which comprises incorporating into an acousticink jet printer an ink and wherein said ink composition selected iscomprised of a colorant and a vehicle component, and which vehiclecomponent is comprised of the condensation product of an organic acidand an amino alcohol.
 17. A process in accordance with claim 15 whereinsaid ink further contains an amide and/or an amino ester.
 18. A processin accordance with claim 15 wherein said mixture contains from about 1to about 99 parts of said amide, and from about 99 parts to about 1 partof said ester.
 19. A process in accordance with claim 17 wherein saidamide is represented by Formulas II or IIa ##STR8## wherein R₁ is analkyl group of from about 1 to about 55 carbon atoms, R₂, R₃, R₄ and R₅are an alkyl, an alkyl alcohol or an alkyl ester group, each alkylcontaining from about 1 to about 55 carbon atoms; and said amino esteris represented by Formula III ##STR9## wherein R₁ is an alkyl group offrom about 1 to about 55 carbon atoms, R₂, R₃, R₄ and R₅ are alkyl, analkyl alcohol or an alkyl ester, each with from about 1 to about 55carbon atoms.
 20. A process in accordance with claim 15 wherein thecolorant is a pigment.
 21. A process in accordance with claim 15 whereinthe colorant is a dye.